In general, an induction heat cooking apparatus is an electric cooking apparatus for performing a cooking function by passing high-frequency current through a working coil or a heating coil and heating a cooking utensil by eddy current flowing when a strong line of magnetic force generated by the high-frequency current passes through the cooking utensil.
In the basic heating principle of the induction heat cooking apparatus, the cooking utensil which is a magnetic body generates heat by induction heating as current is applied to a heating coil, and the cooking utensil itself is heated by the generated heat, thereby cooking food.
An inverter used for the induction heat cooking apparatus serves to switch a voltage applied to the heating coil such that high-frequency current flows in the heating coil. The inverter drives a switching element generally composed of an insulated gate bipolar transistor (IGBT) such that high-frequency current flows in the heating coil, thereby forming a high-frequency magnetic field in the heating coil.
When the induction heat cooking apparatus includes two heating coils, two inverters including four switching elements are required to operate the two heating coil.
FIG. 1 is a diagram explaining a conventional induction heat cooking apparatus.
FIG. 1 shows an induction heat cooking apparatus including two inverters and two heating coils.
Referring to FIG. 1, the induction heat cooking apparatus includes a rectifier 10, a first inverter 20, a second inverter 30, a first heating coil 40, a second heating coil 50, a first resonance capacitor 60 and a second resonance capacitor 70.
In the first and second inverters 20 and 30, two switching elements for switching input voltages are connected in series and first and second heating coils 40 and 50 driven by the output voltages of the switching elements are connected to the contact points of the switching elements connected in series. The other sides of the first and second heating coils 40 and 50 are connected to the resonance capacitors 60 and 70.
The switching elements are driven by a drive unit and are alternately switched at switching times output from the drive unit, thereby applying high-frequency voltages to the heating coils. Since the on/off times of the switching elements driven by the drive unit are controlled to be gradually compensated for, the voltage supplied to the heating coil is changed from a low voltage to a high voltage.
However, the induction heat cooking apparatus includes two inverter circuits including four switching elements in order to operate two heating coils. Therefore, the volume and price of a product increase.
When the number of heating coils is three or more, the number of switching elements increases according to the number of heating coils.